AM Forecast: Possible Thunderstorms

A chance of thunderstorms will threaten the region as scattered showers continue. David Biggar has the forecast for Today in LA on Saturday, April 9, 2016. (Published Saturday, April 9, 2016)

A storm system moving across Southern California was expected to bring cool weather, scattered showers and a chance of thunderstorms through Monday.

Rainfall amounts for Los Angeles and Orange counties, the valleys and Inland Empire should average a half-inch or less, with higher amounts in the foothills and mountains.

Beachgoers were advised to keep caution while in ocean waters around discharging storm drains, creeks and rivers because bacteria, debris, trash and other public health hazards from city streets and mountain areas were likely to enter the ocean, said Jeffrey Gunzenhauser of the LA County of Public Health.

Though discharging storm drains, creeks and rivers comprise only a small portion of the beach, swimmers and surfers could become ill if they enter the water near those sites because of possible contamination from bacterium or chemicals from debris and trash, public health officials said.

PHOTOS: Southern California Storms

The next in the series of storms will take effect Saturday into Sunday, bringing colder air and more rain, NBC4 meteorologist Crystal Egger says. That storm "is poised to deliver a round of heavier showers and perhaps a few thunderstorms," according to the National Weather Service.

Snow levels will be lower but still mostly at or above 6,500 feet through Saturday night and Sunday.

Residual showers will remain Sunday as the system moves out of the region.